With vehicle combinations, instability can occur if the total braking effect of the towing vehicle is greater than that of the trailer vehicle; in this case the vehicle combination can buckle laterally for example. Braking processes of a vehicle combination are therefore in general designed so that the individual vehicles are braked substantially equally.
DE 10 2009 031 851 A1 describes a method for braking a towing vehicle-trailer combination, whereby in a vehicle state with the service brake not operated a trailer pushing the towing vehicle is detected and on reaching and exceeding a prescribed thrust by the trailer, the brake system of the trailer is operated automatically with the service brake of the towing vehicle not operated in order to exert a stabilizing braking effect on the trailer. The thrust by the trailer is determined from a difference or the quotient of the actual engine revolution rate of the towing vehicle and a predetermined target engine revolution rate, i.e. from an increase in the engine revolution rate of the towing vehicle and thereby an engine braking effect, and the trailer is then deliberately decelerated.
DE 203 15 755 U1 describes a brake system in which advanced braking of an overrun brake of the trailer is allowed on releasing the gas pedal of the towing vehicle.
EP 0 914 998 B1 describes a method for matching braking forces between a towing vehicle and a trailer vehicle with which respective speeds of the parts of the vehicle are determined from slip-affected wheel revolution rate signals of the towing vehicle-trailer vehicle and a difference between the time derivatives of the determined speeds of the parts of the vehicle is determined and compared with a limit value, whereby at least one brake control value is changed on exceeding the limit value.
EP 1 439 103 A1 describes a vehicle dynamics control system in which different vehicle dynamic signals from numerous sensors are determined, and on determining unstable driving behavior the brake system of the towing vehicle can be operated, or a braking demand signal is also output to the trailer vehicle.
DE 103 11 838 A1 focuses on determining the danger of a rollover of a vehicle combination, whereby wheel revolution rate signals of the trailer are used.
EP 1 167 141 B1 describes a method for preventing vehicle instabilities in a vehicle combination, with which a difference between the driver's intended course and the actual driving movement is detected in the form of a yaw angle and a braking demand signal may be output to a trailer rear axle.
DE 101 44 299 B4 describes a further method for stabilizing a vehicle combination, with which a trailer brake pressure can be reduced or cyclically modulated in the event of instability.
DE 10 2004 036 089 A1 describes a method for attenuating yaw oscillations of a trailer by operating individual wheel brakes or all wheel brakes of the trailer.